Re: [PATCH] atomic: add atomic_inc_not_zero_hint()

Andrew Morton
2010-11-05T18:08:53Z

On Fri, 05 Nov 2010 19:00:46 +0100
Eric Dumazet <eric.dumazet@gmail.com> wrote:

> Le vendredi 05 novembre 2010 __ 10:20 -0700, Andrew Morton a __crit :
>
> > It totally makes sense to add include/linu/atomic.h for common things.
> > Perhaps there's already code in arch/*/include/asm/atomic.h which
> > should be hoisted up there. But that can't reliably be done until a
> > million files have had their #includes switched :(
> >
>
> Maybe including <linux/atomic.h> only from the end of various
>
> arch/*/include/asm/atomic.h ?

heh, I guess that would work. It breaks the standard way of doing
these things (I think?) so let's not go there unless we have a need?

> In this case, I remove the include <asm/atomic.h> from linux/atomic.h

Oh. Why? I thought it was better the previous, standard way: thou
shalt henceforth include liunx/atomic.h, not asm/atomic.h. And the
presence of linux/atomic.h will in fact trigger the checkpatch warning
telling people to use that when they try to use asm/atomic.h.

> > > +static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
> > > +{
> > > + int val, c = hint;
> > > +
> > > + do {
> > > + val = atomic_cmpxchg(v, c, c + 1);
> > > + if (val == c)
> > > + return 1;
> > > + c = val;
> > > + } while (c);
> > > +
> > > + return 0;
> > > +}
> >
> > Should/could this have implemented a more general
> > atomic_add_not_zero_hint() and made atomic_inc_not_zero_hint() a
> > wrapper around that?
>
> Well, I see no practical use for this, but yes, this could be done.
>
> As atomic_add_not_zero() doesnt exist, I am not sure we need an
> atomic_add_not_zero_hint() yet ?

hm, OK. I was just checking ;)